The power to envisage events, frequently unpleasant, that have not yet taken place was widely accepted in vernacular Celtic tradition, especially in Gaelic Scotland. A person endowed with second sight might see a phantom funeral cortège passing down a road escorting a man then still robust and little expecting to die but who did die shortly afterwards. Having this power does not cause events to take place, nor does it bring any joy in seeing them. Some visions from second sight have taken place. The 17th-century Brahan Seer, Kenneth MacKenzie, foresaw the decline of the Highlands and the building of the Caledonian Canal. Even those not endowed with full powers of second sight might see an occasional ‘forerunner’, like the bright light of a locomotive at night where no trains yet existed but where a railroad line was later to be constructed. The Fenian hero Diorruing was credited with second sight. Ir. fios; ScG taibhse, dà shealladh [two sights]; Manx aa-hilley.
See Norman MacRae, Highland Second Sight (Dingwall, Scotland, 1908).